The present invention relates to an apparatus for producing flakes of cereals, especially soybeans, which can not only be offered as stock feed but are also fit for food. More particularly, the invention relates to an apparatus for producing high-quality soybean flakes by eliminating the toxic substances contained in raw soybeans as well as their peculiar smell by cooking them with superheated steam under pressure.
As is generally known, in the preparation of assorted feed for livestock such as cattle, swines, etc., the materials used therefor are subjected to various types of processing so that they are fit for the intended purpose. Especially, in the case of unprocessed starch of cereals such as wheat, corn, etc., since such starch has the problem in digestion, it is processed into alpha starch to enhance digestiveness. Also, in order to elevate the utilization of protein, such cereals are squashed into flakes by a roll mill. Among the cereals, raw soybean is hard and resistant to the enzymatic action as protein contained therein is not thermally denatured. Also, raw soybean contains toxic substances such as trypsin inhibitor and also has its peculiar smell, so that it is unfit for food.
These demerits of raw soybean, however, can be elevated by a wet heat treatment.
Therefore, in use of raw soybeans for food, it has been generally practiced to heat and moisten them with saturated steam under pressure, squash them into flakes by a roll mill and then dry and cool the flakes.
However, the conventional apparatus for producing such flakes by making use of saturated steam had the problem that when the cooking temperature was elevated for eliminating said demerits of raw soybeans, it was necessarily required to raise the working temperature in the pressure cooker, and as a result, the water content of the raw soybeans being treated would increase to cause break of sticking of the beans when they were sqaushed by the roll mill, makinbK it unable to obtain the high-quality flakes. Also, since the pressure in the cooker must be raised, the loads to the pressure cooker and its appurtenant elements such as locker valves would be increased to reduce their service life. Further, as a great deal of power must be used for holding the high load in the drying step, there was the problem of poor economy.
In view of these problems of the prior art, the present inventors have made further studies for enabling the production of high-quality soybean flakes by eliminating said demerits of raw soybeans and, as a result, succeeded in achieving the present invention.